1. Field of the Invention
The present invention relates to a constant linear velocity (CLV) recording servo circuit for a write-once (WO) type compact disk (CD) which allows a simple structure of an optical pickup and a compatibility with presently used CD players.
2. Related Background Art
With a conventional recording CLV servo circuit as shown in FIG. 8, a revolution sync signal and absolute time code are extracted by reading pre-pits by means of a three-beam method which uses a control beam for tracking a pre-group and erase and write beams disposed at the right and left of the control beam.
Since the conventional method adopts the three-beam method, there is associated with the problems that the structure of an optical pickup is complicated and there is no compatibility with presently used CD players because of prepits.